一. 类图
InterfaceA:虚基类,声明了许多“被装饰者”通用的接口函数
InterfaceB:虚基类,继承自InterfaceA, 声明了许多“装饰者”通用的接口函数
A:被装饰者,实现了InterfaceA中的接口函数
B、C、D:装饰者,每个装饰者都含所有一个InterfaceA的指针,用来指向具体的装饰者。
二. 代码实现
class InterfaceA
{
public:
InterfaceA() {}
virtual ~InterfaceA() {}
virtual string getDescription() = 0;
};
class InterfaceB : public InterfaceA
{
public:
InterfaceB() : InterfaceA() {}
virtual ~InterfaceB() {}
};
class A : public InterfaceA
{
public:
A() {}
~A() {}
string getDescription()
{
return string("I am A");
}
};
class B : public InterfaceB
{
public:
B(InterfaceA* p): m_p(p){}
~B() {}
string getDescription()
{
return m_p->getDescription() + ",decorated by B";
}
private:
InterfaceA* m_p;
};
class C : public InterfaceB
{
public:
C(InterfaceA* p) : m_p(p) {}
~C() {}
string getDescription()
{
return m_p->getDescription() + ",decorated by C";
}
private:
InterfaceA* m_p;
};
int main(int argc, char* argv[])
{
A* pA = new A;
cout<< pA->getDescription(); //直接调用A::getDescription
cout << endl;
//用B来装饰A,形成BA
B* pBA = new B(pA);
cout << pBA->getDescription();
cout << endl;
//用C来装饰BA,形成CBA
C* pCBA = new C(pBA);
cout << pCBA->getDescription();
cout << endl;
getchar();
return 0;
}
运行结果如下图: